Bleaching process



Patented Apr. 12, 1938 UNITED STATES PATENT OFFICE BLEACHING raocnss- NoDrawing. Application March 11, 1937, Serial No. 130,417

4 Claims.

This invention relatesto bleaching processes and more particularly to aprocess for bleaching vegetable and animal substances, such as cotton,rayon, cellulose acetate silk and wool, either waste or raw or in yarnor piece goods.

Standard bleaching processes are relatively complicated and lengthy as,for example, the bleaching of cotton yarn, which involves substantiallyseven steps, as followsz-boiling in caustic, as 2% caustic soda, 1%silicate and 1% sulphonated oil or the like, dropping the above bath andwashing in hot water, dropping and running through hypochloritesolution, to 2 'I'W, dropping and washing in warm water, dropping andsourlng in a hydrochloric acid or sulphurlc acid solution or the like,dropping and washing in warm water, dropping and washing in water towhich is added bluing.

' without interfering with the action of the nascent oxygen.

Still another object is to provide an improved bleaching processwhichwill be efficient, even if the material to be bleached containsinsoluble oils.

Another object is to provide a bleaching process which will leave thematerial, such as rayon,

cellulose acetate silk and cotton, free of oil stains,

chafe marks andso-called niger beads.

Yet another object is to provide a bleaching process which isconsiderably less expensive than most standard bleaching processes forlike material.

Other objects and advantages of the invention will be apparent duringthe course of the following detailed description thereof.

After the material has undergone any preliminary desirable treatment,such as boiling out in order to remove insoluble oils and the like, thematerial is treated, preferably, to a bath containing water, sodiumstearate and sulphonated oil. For example, in this treatment of 100pounds of hose having solid white bodies, heels, toes and tops, thepreferred formula of this bath is:-

220 gallons water 2% sodium stearate 2% sulphonated oil said percentagesbeing by weight and the promaterial washed, for substantially fiveminutes,

portion of ingredients may vary between 200 and 250 gallons water andbetween 2% and 3% sodium stearate and like variations in the sulphonatedoil.

This treatment preferably continues for sub- 5 stantially ten minutes,with the bath at a temperature between 100 F. and 110 F. whereupon thebath may or may not be dropped and the material treated to a bathcontaining sodium hypochlorite and a buffer. The latter may be glues,saponified and/or emulsified fats and oils, sulphonated oils, dextrines,glucose, sugar, fatty alcohols, alkali and alkaline salts.

The sodium hypochlorite and buffer may be mixed together insubstantially the following proportions:-

% by weight sodium hypochlorite 5% by weight buffer However. thepercentages of sodium hypochlorite may vary between 95% and 99% whilethe percentages of buffer may vary between 1% and 5%.

As required, the sodium hypochlorite-buffer mixture may be employedalready mixed, since it has been found that this mixture does not losestrength even after being kept for a considerable period.-

If the first bath is not dropped, from 8% to 10% by weight of the sodiumhypochlorite-buiier mixture is added to it and the material treatedtherein for from 15 to 20 minutes. At the beginning of this lasttreatment, i. e., at the time the sodium hypochlorite-buifer mixture isadded and the material subjected thereto, the temperature of the bathshould be substantially 110 F. It 37 may be less, by allowing the firstbath to cool slightly below F. to F., but it should not be over 110 F.at the start of the treatment with the sodium hypochlorite-buffermixture. Very slowly, the temperature should be brought up to 40 betweenF. and t, at the close of the fifteen to twenty minute led, thetemperature of the bath is between 0 F. and 180 R, whereupon the bath isdropped at once and the in a bath at a temperature between 100 F. and110 F. which bath may comprise:-

200 to 250 gallons water 1% by weight sodium stearate (high titre) Atrace bluing 50 In the event the sodium hypochlorite-buiier mixture isnot added to the first bath, the latter is dropped and the material istreated to a bath containing substantiallyz- 55 200 to 250 gallons water8% to 20% by weight sodium hypochloritebuffer mixture The treatment in.this last bath should be exactly similar to that just outlined.

After treatment as described, the material may be removed from thesodium hypochlorite-bufier mixture bath and suitably dried.

In the bleaching of mercerized cotton and rayon yarns, for example, ofsubstantially pounds weight, the material may be boiled out forsubstantially five mimaes in a bath containing:

200 to 250 gallons water 2% by weight trisodium phosphate 4% by weightsoda ash 2% byweight sodium stearate (such as green soap 145) whereupon,the bath is dropped and the material treated to a bath containingsubstantially:-

100 to 250 gallons water 2% by weight trisodium phosphate 2% by weightsodium stearate (such as green soap 145) 10% by weight mixture It ispreferred that, at the start, this bath be at a temperature ofsubstantially 100 F. and maintained at that temperature for aboutfifteen minutes, whereupon the bath is brought to a boil and boilingmaintained for twenty minutes, after which the bath is dropped and thematerial rinsed in a bath containing about:-

100 to 250 gallons water 2% sodium stearate If and as required bluingFor bleaching raw stock. cotton, the same is, preferably, treated byboilling for one hour in a 5% caustic soda bath, and is then given a hotrinse (180 F. to boiling) for substantially onehalf hour after which itis introducedto a bath which includesz- 2% soda ash 1% sodium stearate8% sodium hypochlorite-bufier mixture sodium hypochlorite-bufi'er Inthis treatment of raw stock cotton, the bath tially as follows for 100pounds hose. A bath is prepared comprising substantially?- 200 to 250gallons water 2% 110.3% sodium stearate 2% to 3% sulphonated oil Thematerial is treated in this bath, with the latter at a temperaturebetween 100 F. and F. for a period of substantially ten minuteswhereupon there is added between 8% to 10% of the sodiumhypochlorite-bufler mixture and treatment continued for from fifteen totwenty minutes, whereupon the temperature is raised to, preferably, 180'F. to 190 F. (altho this temperature may vary between F. and 190 F.) Thehigher temperature range is maintained for about twelve minutes afterwhich the bath is dropped and fresh water of between 200 and 250 gallonscontaining from 1% to 2% sodium stearate (high titre), with bluing ifdesired, is employed as a rinse, the rinse being maintained at atemperature of from 100 F. to 110 F. over a mriod of substantially fiveminutes, whereupon the surplus may be extracted and the material dried.

In the treatment of material with acetate figures, such as hose, 100pounds of such material may be treated to:

200 to 250 gallons water 2% to 3% sodium stearate 2% to 3% sulphonatedoil This treatment may continue for substantially ten minutes at from100 F. to 110 F. after which acetate dyes may be added and treatmentcontinued for substantially thirty minutes at a temperature varyingbetween F. and F. At the expiration of this period the bath is droppedand fresh water added at a temperature of between 100 F. and 110 F., thewater containing substantially 1% sodium stearate and 8% to 10% sodiumhypochlorite-buher mixture. The material is maintained in this bleachingbath for substantially fifteen minutes with the temperature of the bathat between 100 F. and110 F whereupon the temperature is increased, overa period of substantially fifteen minutes to about 170 F. after whichthis treatment is discontinued. the bath dropped, and fresh water atabout 110 Fa employed as a rinse, this water containing about 1% sodiumstearate to 200 to 250 gallons of water. A period of between five andten .w utes will be sufiicient to remove all surplus dyes.

With the treatment described, the chlorine does not attack the materialbeing bleached, due to the proportions of bufiers employed and thetemperatures maintained.

Various changes may be made to the forms of the invention hereindescribed, without departing from the spirit of the invention or thescope of the claims.

What isclaimed is:

1. In a bleabhing process for containing material, the steps subjectingsaid material over a ten and twenty minutes to a bath containing sodiumhypochlorite and a buffer, said bath being at a temperature between 100F. and 110 F., and subsequently bringing the temperature of said bath upto between 140 F. and the boiling temperature of said bath over a.period of between twelve minutes and forty-five minutes, and droppingsaid bath, said bath being the sole major bleaching step of saidprocess.

2. In a bleaching process for fibrous cellulose which consist in offreeing said material of stains, chafe marks and so-called niger beadsthereon, which consist period of between rayon, cotton, celluloseacetate silks and like material, the steps in subjecting said materialover a period of between ten and twenty minutes to a bath consisting ofsodium hypochlorite, a buffer and water, said bath being at atemperature of between 100 F. and 110 F., and subsequentlygraduallyincreasing this temperature over a period -of between fifteenand twenty minutes until the temperature reaches between 160 F. and F.and immediately separating said material and said 3. A bleaching processfor rayon, cotton, cellulose acetate silks and like material, whichconsists in subjecting said material over a period of between ten andtwenty minutes to a bath consisting 0! water, sodium steal-ate andsulphonated oil at a temperature oi between F. and.110 E, dropping saidbath, and subuquently subiecting said material to a bath containingsodium lrypochlorite and a buffer at a temperature of substantially It,bringing said second bath, over a period of between iiiteen and twentyminutes, to a temperature of between 180 F. and 180 R, dr pping saidbath, and washing said material.

4. A bleaching process for fibrous cellulose material containing acetatefigures, which consists in treating said material to a bath comprisingwater, sodium stearate and sulphonated oil for substantially ten minutesat a temperature between 100 1". and 110 F., adding acetate dyes,increasing said temperature to between F. and F., maintaining saidtemperature for substantially thirty minutes. dropping said bath, andtreating said material to a bath comprising water, sodium stearate.sodium hypochlorite and a butler at a temperature between 100 F. and 110F. for substantially fifteen minutes, slowly increasing saidtemperature, over a period of substantially iliteen minutes, tosubstantially 170 F., and immediately dropping said bath.

EDWIN P. SHERMAN.

